石英增强光声光谱技术研究进展

石英增强光声光谱（QEPAS）技术是一种新颖的气体探测技术,具有体积小、灵敏度高等优点,是痕量气体检测技术的研究热点。本文对QEPAS技术的基本原理、发展历史及发展现状进行了综述,并对多种不同结构的QEPAS系统发展情况进行了介绍,最后对该技术的发展前景进行了展望。     

基于雷达测量数据的弹箭扰动源最优估计

为精确计算舰载武器的飞行状态参数,以弹体纵向运动过程为研究对象,推导了包含误差干扰源在内的纵向扰动运动学方程,利用"系数冻结法"及拉普拉斯变换得到解析解,拟合出弹体被动段纵向运动的气动参数公式,采用三坐标雷达测量量作为系统量测方程,从而对气动参数误差干扰源进行最优估计。计算结果表明:该算法可以使俯仰操纵力矩系数导数误差的精度稳定在±0.007(°)~(-1)范围内,阻力系数误差的精度趋于±0.025之间;升力系数误差基本稳定在±0.12之间;俯仰力矩系数对攻角的导数偏差精度稳定在±0.011(°)~(-1)之间;俯仰阻尼力矩系数误差的精度收敛于±0.009(°)~(-1)之间,且算法收敛速度快,可为重构高精度的弹道参数提供支撑。     

不同钙源种类对CaTi2O5粒子的光催化性能影响

采用溶剂热法制备了CaTi2O5微纳结构.用X射线衍射(XRD)、扫描电子显微镜(SEM)和比表面积分析仪(BET)对样品进行了表征,并用紫外-可见吸收光度计分析样品对光的吸收特性,研究不同钙源种类对CaTi2O5样品的物相、微观形貌及光催化性能的影响.结果表明:CaTi2O5样品更有利于降解甲基橙溶液.钙源为CaCl2所制备的CaTi2O5样品的结晶度高、颗粒大小均匀,具有低的反射率和高的吸收率,高的比表面积(112.34 m2·g-1),因此样品呈现出较高的光催化性能.     

Effect of quadratic pressure gradient term on a one-dimensional moving boundary problem based on modified Darcy’s law

A relatively high formation pressure gradient can exist in seepage flow in low-permeable porous media with a threshold pressure gradient, and a significant error may then be caused in the model computation by neglecting the quadratic pressure gradient term in the governing equations. Based on these concerns, in consideration of the quadratic pressure gradient term, a basic moving boundary model is constructed for a one-dimensional seepage flow problem with a threshold pressure gradient. Owing to a strong nonlinearity and the existing moving boundary in the mathematical model, a corresponding numerical solution method is presented. First, a spatial coordinate transformation method is adopted in order to transform the system of partial differential equations with moving boundary conditions into a closed system with fixed boundary conditions; then the solution can be stably numerically obtained by a fully implicit finite-difference method. The validity of the numerical method is verified by a published exact analytical solution. Furthermore, to compare with Darcy’s flow problem, the exact analytical solution for the case of Darcy’s flow considering the quadratic pressure gradient term is also derived by an inverse Laplace transform. A comparison of these model solutions leads to the conclusion that such moving boundary problems must incorporate the quadratic pressure gradient term in their governing equations; the sensitive effects of the quadratic pressure gradient term tend to diminish, with the dimensionless threshold pressure gradient increasing for the one-dimensional problem.     

The effect of a permanent dipole moment on the polar molecule cavity quantum electrodynamics

A dressed-state perturbation theory beyond the rotating wave approximation(RWA) is presented to investigate the interaction between a two-level electronic transition of polar molecules and a quantized cavity field. Analytical expressions can be explicitly derived for both the ground- and excited-state-energy spectrums and wave functions of the system, where the contribution of permanent dipole moments(PDM) and the counter-rotating wave term(CRT) can be shown separately.The validity of these explicit results is discussed by comparison with the direct numerical simulation. Compared to the CRT coupling, PDM results in the coupling of more dressed states and the energy shift is proportional to the square of the normalized permanent dipole difference, and a greater Bloch–Siegert shift can be produced in the giant dipole molecule cavity QED. In addition, our method can also be extended to the solution of the two-level atom Rabi model Hamiltonian beyond the RWA.     

强流RF 离子源研制及初步实验

介绍了RF离子源驱动源的结构设计及RF线圈的热流固耦合分析。RF离子源采用外置天线的感应耦合方式,采用双射频驱动源设计,每个射频驱动源功率约60kW,总体功率为120kW,可产生均匀高密度的等离子体,以满足稳定的长脉冲运行的要求。在完成上述工作的基础上完成了RF离子源样机组装和初步实验测试。     

ILC正电子源靶接触热传导冷却技术的初步研究

国际直线对撞机（ILC）正电子靶沉积的热功率将超过20 kW,传统的冷却方式已无法满足要求。美国Argonne国家实验室提出了摩擦接触热传导冷却的方法。根据Argonne实验室的研究方案,设计了一种旋转摩擦接触冷却的简化装置,根据热传导理论,结合ANSYS软件模拟了旋转冷却过程中的温度分布,理论上验证了方法的可行性。按照模拟的参数和结果,进行了摩擦接触热传导冷却实验,通过实验结果和数据分析证实了,低温区（20℃~50℃）有良好的冷却效应,初步验证了摩擦接触热传导冷却方案的有效性。A new scheme that cooling international Linear Collider (ILC) positron source target by touching thermal conduction (TTC) is presented by Argonne National Laboratory (ANL).Recent results of simulation for cooling the iron targets with 300 and 450 W heat reservoir by ANSYS and experiment of cooling the iron target with 300 and 450 W friction heat reservoir at Institute of Modern Physics (IMP),Chinese Academy of Sciences (CAS),have proved that the TTC has good cooling effect in low temperature zone (20℃~50℃),and preliminarily verified the feasibility of TTC for cooling the ILC positron source target.     

小型球形脉冲氙灯光谱分析与实验测定

作为分析仪器和医疗仪器光源,脉冲氙灯的光谱特性直接影响着仪器的整体性能。为了研究脉冲氙灯放电回路参数及几何参数对其光谱特性的影响,利用气体放电理论分析了脉冲氙灯发光过程,设计了光谱检测系统,实验测定了脉冲氙灯在不同放电参数下的光谱特性。结果表明：脉冲氙灯光谱由连续谱和线状谱组成,连续谱有离子复合和韧致辐射产生,线状谱由电子能级跃迁产生。相对光谱辐射能量随着放电电压升高呈近似线性增长、并随着储能电容的变大而变大。在放电电压较低时,弧长较短时相对光谱辐射能量较大;在放电电压较大时,弧长越长相对光谱辐射能量越大。对于脉冲氙灯工作参数选取以及应用生产具有重要的意义。     

Detection of supernova neutrinos at spallation neutron sources

After considering supernova shock effects, Mikheyev-Smirnov-Wolfenstein effects, neutrino collective effects, and Earth matter effects, the detection of supernova neutrinos at the China Spallation Neutron Source is studied and the expected numbers of different flavor supernova neutrinos observed through various reaction channels are calculated with the neutrino energy spectra described by the Fermi-Dirac distribution and the "beta fit"distribution respectively. Furthermore, the numerical calculation method of supernova neutrino detection on Earth is applied to some other spallation neutron sources, and the total expected numbers of supernova neutrinos observed through different reactions channels are given.     

A review of research progress in air-to-water sound transmission

International and domestic research progress in theory and experiment and applications of the air-to-water sound transmission are presented in this paper. Four classical numerical methods of calculating the underwater sound field generated by an airborne source, i.e., the ray theory, the wave solution, the normal-mode theory and the wavenumber integration approach, are introduced. Effects of two special conditions, i.e., the moving airborne source or medium and the rough air-water interface, on the air-to-water sound transmission are reviewed. In experimental studies, the depth and range distributions of the underwater sound field created by different kinds of airborne sources in near-field and far-field, the longitudinal horizontal correlation of underwater sound field and application methods for inverse problems are reviewed.